There’s not much point in deploring the over-tweeters of the under-important. Just unfollow them. (Except, of course, where the elaborate social politics of Twitter forbid unfollowing.) But two-faced Twitter has also brought about, in its opposite aspect, the very last thing to have been expected from the internet: a renovation of the epigram or aphorism, a revaluation of the literary virtues of terseness and impersonality.